Preparation of sulfurized phenol additives intermediates and compositions

ABSTRACT

A process is described wherein olefins or acetylenic compounds are reacted with sulfurised intermediates to produce nitrile seal compatible additives. Olefin or acetylinic compound reaction with sulfurised compounds e.g. sulfurised phenols results in low chlorine additives. Also disclosed is a process for the production of low chlorine intermediates.

This is a continuation of application Ser. No. 08/750,947, filed Jan.30, 1997, now U.S. Pat. No. 5,827,806.

The present invention is concerned with a process for preparingsulfurised phenol lubricating oil additives, lubricant oil compositionsand concentrates containing such additives, with the use of suchadditives in lubricant oil formulations and with the preparation and useof intermediates for such additives.

Power trains, for example, automotive power trains, require shaft andbearing seals to prevent the ingress of contaminants. Seal life dependson, inter alia, the suitability of the chosen seal for the use to whichit is put, the degree of care used in installing the seal, thetemperature to which the seal is exposed during use, the nature of thelubricants with which the seal comes into contact during use, and thecondition of the surface(s) with which the seal comes into contactduring use. Seal failure will in most cases lead to a leakage oflubricant, which is increasingly regarded as unacceptable, and sealswhich can no longer perform their intended function must normally bereplaced. There is thus a need for the life of seals to be prolonged foras long as possible.

There is also a strong desire to develop lubricating oil additives whichhave reduced levels of chlorine so that their use in finished oilformulations does not contribute to high levels of chlorine in thefinished lubricating oil formulation. The presence of chlorine inlubricating oils is a problem from a waste disposal and environmentalpoint of view. When lubricating oils containing high levels of chlorineare destroyed after use e.g. by incineration harmful chlorinated andpolychlorinated biphenyls may be produced. Waste disposal ofcompositions based on chlorine-containing additives is therefore aproblem; it would be advantageous to be able to produce chlorine-freeadditives or additives containing low levels of chlorine.

Sulfur-containing additives have been widely used in various lubricants,e.g., crankcase lubricating oils, or gear lubricants, and in variousfunctional fluids, e.g., hydraulic fluids, automatic transmission fluidsand heat transfer fluids. One of the most common of suchsulfur-containing additives are the sulfurised phenols such as alkylsubstituted phenolsulfides, disulphides, polysulfides, salts thereof,overbased salts thereof, and mixtures thereof. These additives functionas oxidation inhibitors, antiwear additives and load carrying additivesand detergents for these different category of fluids.

Whilst these sulfur-containing additives have been found to be quiteeffective for the above mentioned functions, they have generally beenfound to be corrosive to metals such as copper and copper alloys whichare widely used as bearings and bearing liners. They have also beenfound to cause the degradation of elastomeric materials which are usedas seals or sealant devices. This is a particular problem withsulfurised phenol additives. It would be desirable to be able to usehigher levels of sulfurised phenols however the problems associated withcopper corrosion and/or seals precludes this. It is also desirable to beable to keep the ash content of lubricating oil formulations as low aspossible. It is believed that the problems associated with sulfurisedphenols are due to the presence of sulfur species, including elementalsulfur, which are sometimes referred to as labile, free or activesulfur.

There have been various attempts in the prior art to provide sulfurisedphenols and other sulfur containing additives for lubricating oils whichdo not have a detrimental effect on the compatibility of elastomericseals when exposed to such seals in oil formulations and/or whichexhibit reduced copper corrosion.

In U.S. Pat. No. 4,228,022, a process is described in which a sulfurisedphenate is reacted with sufficient α-olefin (C₁₅₋₁₈) to ensure that thefinal product has substantially no residual free sulfur so that theproduct has anti-corrosive properties; that is, so that it does notcorrode metallic engine parts. The level of α-olefin which may be usedis up to 25 wt % based on the amount of phenol used to prepare thephenate. More generally it is indicated that the olefins preferablycontain 10 to 30 carbon atoms, especially 15 to 20 carbon atoms, and maybe straight or branched chain. The performance of elastomeric materialsis not discussed.

International Specification No. WO 85/04896 indicates that labilesulfur-free additives for lubricants can be obtained by treatingsulfurised phenol additives containing labile or active sulfur withcopper, or copper and another material reactive with labile sulfur, orwith a mono-olefin, particularly an α-olefin; α-olefins containing 4 to30 carbon atoms, especially 10 to 20 carbon atoms, being preferred. Theolefin is used at up to 10 wt % based on the sulfurised additive andonly in an amount sufficient to remove the active sulfur present. It isstated that the metal corrosivity and the degradation of elastomericmaterials which are caused by labile sulfur-containing additives can besubstantially eliminated. There is no reference to specific elastomericmaterials and the olefins mentioned in the Examples are C₁₂, C₁₅₋₁₈ orC₁₆₋₁₈ α-olefins.

In U.S. Pat. No. 4,309,293, a process is described wherein sulfurisedphenols derived from the reaction of sulfur monochloride and substitutedphenols are further reacted with vinyl ethers. The vinyl ether reactswith the phenolic hydroxyl groups present. There is no reference to theperformance of elastomeric materials.

Whilst the prior art has gone some way to overcome the problemsassociated with the use of sulfurised phenols in lubricating oilcompositions which exhibit copper corrosion problems, there has beenrelatively little improvement in the compatibility of such compositionswith elastomeric seals and more specifically compatibility with nitrileseals. There is a need therefore for sulfurised phenol additives whichshow further improvements in seal compatibility, especially nitrile sealcompatibility, and for improved processes for making such additives.Furthermore there is also a need for such additives and processes whichdo not exacerbate the problems associated with the presence of chlorinein lubricating oil formulations and thus enable the use of high levelsof sulfurised phenols. This is desirable because the use of higherlevels of sulfurised phenols in lubricating oil formulations may allowthe levels of metal containing detergents and other metal containingadditives which contribute to the ash levels in lubricating oilformulations to be reduced. The problems are particularly severe forlubricants for heavy duty diesel engines which normally require highlevels of sulfur-containing additives. A lubricant for a heavy dutydiesel engine will typically contain up to 3 mass % of asulfur-containing compound such as a sulfurised phenol. There is a needtherefore for sulfurised phenol additives which can be used at highlevels in lubricating oil compositions which are compatible withelastomeric seals and which also do not contribute significantly to thechlorine content of the composition.

The applicants have also surprisingly found an improved process forproducing sulfurised phenol intermediates which may be advantageouslyused for the production of sulfurised additives of the present inventionor which may advantageously be used in their own right as additives inlubricating oil compositions especially for formulating lubricating oilcompositions with low levels of chlorine.

The present invention therefore provides a process for preparing anoil-soluble sulfurised phenol additive compatible with nitrile sealswhich process comprises the steps of:

(i) reacting together at a temperature of at least 100° C. anoil-soluble active-sulfur containing sulfurised phenol intermediate; andan olefin or an acetylenic compound in an amount in excess of thatrequired to react with the active sulfur present in the sulfurisedphenol intermediate; and

(ii) removing substantially all unreacted olefin or acetylenic compound.

The present invention also provides an oil-soluble sulfurised phenoladditive compatible with nitrile seals obtainable by the above process.

The present invention further provides for a lubricating oil compositionwhich comprises lubricating oil as a major component and an oil-solublesulfurised phenol additive obtainable by the above process.

The present invention also provides for a lubricating oil concentratewhich comprises one or more lubricant additives, and an oil solublesulfurised phenol additive obtainable by the above process andlubricating oil.

The present invention further provides for the use of an oil solublesulfurised phenol additive obtainable by the above process to enhancethe nitrile elastomer seal compatibility and/or the copper corrosionproperties of a lubricating oil composition.

Suitable olefins for use in the preparation of the oil-solublesulfurised phenol additives of the present invention includemono-olefins, di-olefins, tri-olefins or higher homologues. By suitableis meant olefins which are capable of reacting with active sulfur andwhose properties are such that the excess of such olefins used in theprocess of the present invention may be removed from the reactionmixture without resulting in significant decomposition of the sulfurisedphenol additive. Preferred olefins are those with a boiling point of upto 200° C. and most preferably have a boiling point in the range of 150°C. to 200° C.

Any mono-olefin meeting the above requirements may be used in thepreparation of additives of the present invention. The mono-olefins maybe unsubstituted aliphatic mono-olefins meaning that they contain onlycarbon and hydrogen atoms, or they may be substituted with one or moreheteroatoms and/or heteroatom containing groups e.g. hydroxyl, amino,cyano. An example of a suitable cyano substituted mono-olefin isfumaronitrile. The mono-olefins may also be substituted with aromaticfunctionality as for example in styrene. The mono-olefins may containfor example ester, amide, carboxylic acid, carboxylate, alkaryl,amidine, sulfinyl, sulfonyl or other such groups. It is preferred thatthe mono-olefins are aliphatic and are not substituted with heteroatomsand/or heteroatom containing groups other than hydroxyl or carboxylategroups. The mono-olefins may be branched or non-branched it is preferredthat they are branched. By branched is meant that the olefin containsone or more tertiary carbon atoms i.e. carbon atoms that are bound to atleast three other carbon atoms or when one or more heteroatoms orheteroatom containing groups are present in the olefin one or more ofthese carbon atoms may be a heteroatom.

The mono-olefin preferably has from 4 to 36 carbon atoms and mostpreferably 8 to 20 carbon atoms. The mono-olefin may for example be anα-olefin. Examples of α-olefins which may be used in the process of thepresent invention include; 1-butene, 1-pentene, 1-hexene, 1-heptene,1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tridecene, 1-tetradecene,1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene,1-eicosene, 1-heneicosene, 1-docosene, 1 tetracosene, 1-pentacosene,1-hexacosene, 1-octacosene, and 1-nanocosene. The α-olefin may be amixture of α-olefins such as the following commercially availablemixtures; C₁₅-C₁₈, C₁₂-C₁₆, C₁₄-C₁₆, C₁₄-C₁₈, C₁₆-C₂₀, C₂₂-C₂₈, and C₃₀₊(Gulftene available from the Gulf Oil Company).

Another class of mono-olefins are those containing a saturated alicyclicring and one double bond e.g. an exocyclic double bond. The alicyclicring preferably contains at least six carbon atoms, and, advantageously,the alicyclic ring is substituted by a methylene bridging group thatforms a four-membered ring with three of the ring carbon atoms. Themethylene carbon atom in such a bridging group may be substituted,preferably by two methyl groups e.g. as β-pinene. Other examples ofmono-olefins include α-pinene, methylene cyclohexane, camphene, andmethylene cyclopentane etc. and unsaturated compounds such as thevarious derivatives of acrylic acid such as acrylate, methacrylate andacrylamide derivatives.

An example of a suitable mono-olefin is the C₁₂ tetramer of propylene.Other suitable mono-olefins include oligomers of for example ethylene.Typically oligomeric olefins are mixtures; therefore mixtures ofoligomeric mono-olefins may be used such as mixtures of propyleneoligomers.

The di-olefins, tri-olefins and higher homologues may be any sucholefins which meet the above identified performance requirement for theolefin. Preferred di-olefins, tri-olefins and higher homologues arethose selected from;

(a) an acyclic olefin having at least two double bonds, adjacent doublebonds being separated by two saturated carbon atoms; or

(b) an olefin comprising an alicyclic ring, which ring comprises atleast eight carbon atoms and at least two double bonds, each double bondbeing separated from the closest adjacent double bond(s) by twosaturated carbon atoms.

The preferred olefins of group (a) are unsubstituted or substitutedlinear terpenes. Unsubstituted linear terpenes for use in accordancewith the invention may be represented by the formula (C₅H₈)_(n) whereinn is at least 2, that is, a terpene containing carbon and hydrogen atomsonly. An example of an unsubstituted linear terpene is squalene (inwhich n in the above formula is 6). Possible substituents for linearterpenes to be used in accordance with the invention are, for example,hydroxyl groups. Suitable substituted terpenes include farnasol andgeraniol with geraniol being preferred. Other examples of suitabledi-olefins include dicyclopentadiene, dipentene, 1,3-cyclohexadiene,1,5,-cyclooctadiene, methylcyclopentadiene, limonene and1,4-cyclohexadiene and polybutadiene etc.

If desired, the group (b) olefins may contain at least three doublebonds, each end of each double bond being separated from each adjacentdouble bond by two saturated carbon atoms. An example of a suitablegroup (b) olefin having three double bonds is 1,5,9-cyclododecatriene.An example of another tri-olefin is cycloheptatriene.

The acetylenic compounds for use in the process of the present inventionfor producing additives are compounds which are capable of reacting withactive sulfur and whose properties are such that the excess of suchcompounds used in the process of the present invention may be removedfrom the reaction mixture without resulting in significant decompositionof the sulfurised phenol additive. An example of a suitable acetylenematerial is phenyl acetylene.

The preferred olefins for use in the process of the present inventionare di-olefins such as for example those as defined in a) above, mostpreferably they are 1,5-di-olefins such as 1,5-cyclooctadiene andgeraniol. Olefins are preferred to acetylenic compounds.

More than one olefin may of course be used if desired. Where two or moreolefins are used, these need not be compounds from the same group. Thus,for example mixtures of mono and diolefins may be used although this isnot preferred.

In carrying out the process for preparing sulfurised phenol additivesaccording to the present invention the olefin or acetylenic compound andactive sulfur-containing sulfurised phenol intermediate may be added inany order. Thus, for example, the olefin or acetylenic compound may beintroduced into a vessel already containing the sulfurised phenolintermediate, or vice versa, or the two materials may be introducedsimultaneously into the vessel. This process may be carried out in asuitable solvent for the reactants and/or products. This is a solventwhich does not cause problems in removal which effect stability of theproduct. An example of a suitable solvent which may be used is SN150basestock. In some instances the olefin when used in a sufficient amountmay act as a solvent for the reaction.

In the process for the preparation of additives of the present inventionthe mass ratio of sulfurised phenol intermediate to olefin or acetyleniccompound is such that the olefin or acetylenic compound is always inexcess of that required to react with the active sulfur present in theintermediate. The exact levels will depend on the nature of the olefinor acetylenic compound i.e. whether or not for example it is a mono-dior tri olefin, its molecular weight and the molecular weight of thesulfurised phenol intermediate used, its level of sulfur and level ofactive sulfur. For example when the olefin is C₁₂ propylene tetramer theratio is preferably in the range 1.3:1 to 9:1.

It is preferred that the reaction between the sulfurised phenolintermediate and the olefin or acetylenic compound is carried out at anelevated temperature of greater that 120° C. and most preferably between120° C. to 250° C. and for 0.5 to 60 hours. It has surprisingly beenfound that nitrile seal compatibility improves with the use of higherlevels of olefin or acetylenic compound in the reaction. It is preferredtherefore that the levels of olefin or acetylenic compound used are atleast 100% in excess of the stoichiometric amount required to react withthe active sulfur present in the sulfurised phenol intermediate. It ismost preferred that they are used in at least a 400% stoichiometricexcess and more preferably are used in the range of 400 to 800% inexcess of stoichiometry in relation to the active sulfur present. It hasalso been found that the nitrile seal compatibility of the productimproves with higher reaction temperatures and/or reaction times.

Substantially all of the unreacted olefin or acetylenic compound isremoved preferably by means of vacuum distillation, post reaction, orother separation methods. The exact method used will depend on thenature of the olefin or acetylenic compound used. In some circumstancesthe unreacted olefin or acetylenic compound may be removed by simplyapplying a vacuum to the reaction vessel or may require the use ofapplied heating to elevate the temperature of the reaction mixture.Preferably the unreacted material is removed by means of vacuumdistillation and where necessary with the use of heating. Othermaterial, such as volatile material when vacuum distillation is used,may be removed at the same time as the unreacted olefin or acetyleniccompound. By substantially all the unreacted olefin or acetyleniccompound is meant that proportion which may be removed by the use ofsuch techniques as for example vacuum distillation. Typically there willbe less than 3 wt % of unreacted olefin or acetylenic compound remainingin the product and preferably between 0 to 3 wt % and most preferably0.5 wt % or less. The residual material may not correspond exactly tothe composition of the olefin or acetylenic compound used e.g. when amixture of olefin oligomers are used or for example a mixture ofmono-olefins, di-olefins, or mono- and di-olefins. This residualmaterial may comprise as a major proportion the higher molecular weightfractions present in the original olefin composition or mixture used.For example, in the case of the olefin being a propylene tetramer, whichis typically a mixture of olefins, residual material after removal ofexcess olefin may comprise a high proportion of for example pentamer andhigher homologues of propylene.

It has been found that removal of substantially all the unreacted olefinor acetylenic compound is required so that lubricating oil compositionscomprising olefin or acetylenic compound reacted additives achieveacceptable performance in the Panel Coker test. This is an industrystandard bench test which is used to screen additives in lubricating oilformulations to evaluate their efficacy as for example antioxidantsand/or their ability to prevent deposition of carbonaceous deposits bymaintaining such deposits in a dispersed form in the oil. If the excessolefin or acetylenic compound is not removed inferior Panel Cokerperformance of the oil is observed. This is a particular problem withdi-olefins.

It is a further possibility that the intermediate is not isolated fromits reaction mixture before being used in the process for the productionof additives according to the present invention. On completion of thereaction between sulfur monochloride and the phenol, using for examplethe preferred process of the present invention, the temperature of theintermediate reaction mixture is increased to the olefin or acetyleniccompound reaction temperature and the reaction carried out. Thisincrease in temperature may be achieved by means of a ramped temperatureincrease to the reaction temperature. The olefin or acetylenic compoundmay be added to the intermediate reaction mixture before during or afterthe temperature increase.

In a preferred embodiment the process for the preparation of additivesof the present invention utilises a catalyst for the reaction betweenthe olefin or acetylenic compound and the sulfurised phenolintermediate. Suitable catalysts include sulfurisation catalysts andnitrogen bases. The preferred catalysts are nitrogen bases. Suitablenitrogen bases include nitrogen-containing ashless dispersants which arecommercially available materials such as Mannich bases and the reactionproducts of hydrocarbyl acylating agents with amines, in particularpolyisobutenyl succinimides may be used; these may be prepared by any ofthe conventional routes. It is preferred to minimise incorporation ofchlorine into the additive by the dispersant, for example by preparing apolyisobutenyl succinimide in which polyisobutenyl succinic anhydride isprepared using the so-called thermal process in which polyisobutene isreacted directly with maleic anhydride, without the use of chlorine,before reaction with the amine to produce the final dispersant. Othersuitable nitrogen bases include simple amines such as for example mono-,di-, and tri-butylamines, polyamines such as for examplediethylenetriamine (DETA), triethylenetetramine (TETA) andtetraethylenepentamine (TEPA), cyclic amines for example morpholines andaromatic amines such as commercial diphenylamines. A particularlysuitable amine is n-octylamine. It has also surprisingly been found thatnitrile seal compatibility improves with the use of increasing levels ofcatalyst to prepare the additives of the present invention.

In a further aspect of the present invention it has been found that thereaction with olefin or acetylenic compound has the benefit of reducingthe level of chlorine in sulfurised compounds such as for example thesulfurised intermediates of the present invention or any sulfurisedcompound which has been prepared using sulfur monochloride, sulfurdichloride or mixtures thereof.

The present invention therefore further provides a process for reducingthe chlorine content of an oil-soluble sulfurised compound which processcomprises the steps of:

(i) reacting together at a temperature of at least 100° C.

a) an oil-soluble sulfurised compound prepared using either sulfurmonochloride, sulfur dichloride or mixtures thereof, and having achlorine content of 100 ppm or greater; and

b) an olefin or an acetylenic compound; and

(ii) removing substantially all unreacted olefin or acetylenic compound.

This reaction has been found to be particularly effective in reducingthe levels of chlorine in sulfurised phenols which have been preparedusing S₂Cl₂ and in particular is effective with sulfurised intermediatesprepared by the process of the present invention as described below.Thus chlorine levels of 500 ppm or less and as low as 300 ppm and even100 ppm may be achieved in the final additive after reaction with anolefin or acetylenic compound. The magnitude of this reduction isincreased with the use of higher reaction temperatures between thesulfurised additive and olefin or acetylenic compound. In this processit is preferred that the sulfurised additive is a sulfurised phenol andmost preferably is a sulfurised intermediate of the present invention asdescribed below.

The oil-soluble active sulfur-containing sulfurised phenol intermediatesfor use in the production of oil-soluble sulfurised phenol additivesaccording to the present invention include mono-, di- and polysulfidesof phenols or hydrocarbyl group substituted phenols such as alkylphenols. The hydrocarbyl group substituted phenols may contain one ormore hydrocarbyl substituent groups per aromatic ring.

Suitable intermediates for use in the process of the present inventionfor preparing additives may be represented by the general formula I:

wherein R represents a hydrocarbyl radical, n is an integer of 0 to 20,y is an integer of 0 to 4 and may be different for each aromatic nucleusand x is an integer of from 1 to 7 typically 1 to 4. The average numberof carbon atoms per hydrocarbyl radical being sufficient to ensureadequate solubility in oil of the sulfurised hydrocarbyl groupsubstituted phenol intermediate. The individual groups represented by Rmay be the same or different and may contain from 1 to 50, preferably 5to 30 and most preferably 8 to 20, carbon atoms. Preferably thehydrocarbyl radical R represents an alkyl group. Preferred sulfurisedalkyl phenol intermediates are those wherein n is 0 to 4, y is 1 or 2and may be different for each aromatic nucleus, x is 1 to 4 and R is 8to 20 carbon atoms most preferably 9 to 12 carbon atoms. Thesesulfurised hydrocarbyl group substituted phenol intermediates may bemixtures of intermediates of the above general formula and may includeun-sulfurised phenolic material. It is preferred that the level ofun-sulfurised phenolic material is kept to a minimum. The final productmay contain up to 20% preferably up to 12% by weight of un-sulfurisedphenolic material. One preferred group of sulfurised hydrocarbyl groupsubstituted phenol intermediates are those with a sulfur content ofbetween 4 and 16 mass % preferably 4 to 14% and most preferably 6 to 12mass %. The sulfurised additives, which will normally comprise a mixtureof different compounds, typically contain at least some sulfur which iseither free, or is only loosely bonded; the sulfur thus being availableto attack nitrile elastomeric seals and is referred to as active sulfur.This active sulfur may be present in the form of polysulfides forexample when x is three or greater in formula I; in this form the activesulfur may be present at levels which are typically up to 2 wt % ormore.

These hydrocarbyl group substituted phenol intermediates may be preparedby methods which are well known in the art. Such as by the reaction ofhydrocarbyl group substituted phenols in the presence of a sulfurisingagent; the sulfurising agent being an agent which introduces S_(X)bridging groups between phenols where x is 1 to 7. Thus the reaction maybe conducted with elemental sulfur or a halide thereof such as sulfurmonochloride or sulfur dichloride.

The hydrocarbyl group substituted phenols may be any phenol of generalformula II

wherein R and y are as defined above. Mixtures of phenols of generalformula II may be used.

It is preferred that the oil soluble sulfurised phenol intermediate isderived from sulfur monochloride and has low levels of chlorine thus ina further aspect the present invention provides a process for preparingan oil-soluble sulfurised phenol intermediate comprising less than 1000ppm of chlorine and at least 4% by weight of sulfur which processcomprises:

a) reacting together sulfur monochloride and at least one phenol ofgeneral formula II in a reaction mixture and at a temperature in therange of −50 to 250° C.

wherein the mole ratio of phenol: S₂Cl₂ in the reaction mixture isgreater than 1.7:1.

In this preferred process for the production of oil soluble sulfurisedintermediates it is preferred that R in the phenol of general formula IIcontains 5 to 30 and most preferably 8 to 20, carbon atoms and y is 1 or2. It is preferred that the phenol is a mixture of phenols and as suchhas an average molecular weight of 164 or greater, preferably 200 orgreater and most preferably 220 or greater e.g. 250 or greater. Mostpreferred mixtures are mixtures of mono- and di-substituted phenols ofgeneral formula II e.g. mixtures of para- and ortho/para substitutedphenols. Preferably in the process for producing the intermediate thephenolic compound comprises between 20 and 90% by weight of paramono-substituted phenolic compound and between 10 and 80% by weight ofat least one di-substituted phenolic compound which has at least onereactive ortho position free and preferably is anortho-/para-di-substituted phenolic compound. It is preferred that thephenols of general formula II for use in this process are not hinderedphenols although they may be mixtures of phenols which comprise a minorproportion such as less than 25 wt % e.g. less than 10 wt % of hinderedphenol. By hindered phenols is meant phenols in which all the ortho andpara reactive sites are substituted, or sterically hindered phenols inwhich, either both ortho positions are substituted or only one orthoposition and the para position are substituted and, in either case, thesubstituent is a tertiary alkyl group e.g. t-butyl. It is preferred thatfor a given mixture of mono and di-alkyl substituted phenols e.g. nonylsubstituted, that the monosubstitutedphenol is present in at least 20 wt% and preferably in the range 10 to 65 wt %. When the average molecularweight is greater than 250 but less than 300 it is preferred that themixture of phenols comprises 50 wt % or greater preferably 60 wt % orgreater e.g. 65 wt % of mono-substituted phenol. When the averagemolecular weight is greater than 300 it is preferred that the phenolmixture comprises 50 wt % or greater preferably 70 wt % or greater e.g.80 wt % of di-substituted phenol. It is preferred that the mole ratio ofphenol to sulfur monochloride is 2 or greater and most preferably is 2.2or greater.

In this aspect of the present invention this improved process producesintermediates which have low levels of chlorine whilst at the same timeallowing for the required levels of sulfur and conversion of phenolicmaterial to be achieved. Preferably the chlorine content is 900 ppm orless e.g. 800 or less and most preferably 500 ppm or less. The level ofsulfur, the required conversion of phenolic material to keep theun-sulfurised material to a minimum and the chlorine levels are linked.It is difficult to keep chlorine levels low whilst increasing sulfurcontent and achieving the desired conversion, because more chlorinecontaining starting material i.e. S₂Cl₂ is usually required to achievethese targets; the task is to be able to achieve low chlorine whilst atthe same time not having a detrimental effect on the other two factors.In this process for producing the intermediate it is preferred that thereaction is carried out in the temperature range of −15 or −10 to 150°C. e.g. 20 to 150° C. and preferably 60 to 150° C. It is most preferredthat the reaction is carried out at less than 110° C.; the use ofreaction temperatures below 110° C. with certain phenols results inintermediates with lower levels of chlorine. Typically the reactiontemperature is between 60 and 90° C. Preferably the sulfur monochlorideis added to the reaction mixture at a rate of 4×10⁻⁴ to 15⁻⁴ cm³ min⁻¹g⁻¹ phenol. If the reaction mixture is not adequately mixed during thisaddition the chlorine content of the intermediate may increase. Theresultant product preferably has a sulfur content of at least 4% e.g.between 4 and 16%, more preferably 4 to 14% and most preferably at least6% e.g. 7 to 12%. The process has the advantage of not requiringcomplicated post reaction purification steps in order to reduce thelevels of chlorine in the intermediate product.

When the preferred intermediates derived from sulfur monochloride areused in the above process for the production of sulfurised phenoladditives according to the present invention this not only results innitrile seal compatible additives due to the olefin treatment but alsoresults in additives which have low chlorine levels. When the sulfurisedphenol additive is derived from these preferred sulfurised intermediatesthe final additive product may contain low levels of chlorine that isless than 1000 ppm, preferably 900 ppm or less e.g. 800 ppm or less andmost preferably 500 ppm or less.

The additives, or intermediates of the present invention may be used toprepare phenates and overbased phenates by reaction with alkali oralkaline earth metal salts or compounds. The phenates and overbasedphenates derived from the intermediates of the present invention or fromadditives derived from such intermediates may also have low levels ofchlorine e.g. less than 1000 ppm and as low as or lower levels thanthose present in the additive or intermediate used in their preparation.Phenates may contain a substantially stoichiometric amount of the metalin which case they are usually described as normal or neutral salts, andwould typically have a total base number or TBN (as may be measured byASTM D2896) of from 0 to 80. It is possible to include large amounts ofa metal base by reacting an excess of a metal compound such as an oxideor hydroxide with an acidic gas such as carbon dioxide. The resultingoverbased phenates comprise neutralised detergent as the outer layer ofa metal base (e.g. carbonate) micelle. Such overbased phenates may havea TBN of 150 or greater, and typically of from 250 to 450 or more. Themetals are in particular the alkali or alkaline earth metals, e.g.,sodium, potassium, lithium, calcium, and magnesium. The most commonlyused metals are calcium and magnesium, which may both be present inphenates used in a lubricant, and mixtures of calcium and/or magnesiumwith sodium. Particularly convenient phenates are neutral and overbasedcalcium phenates and sulfurized phenates having a TBN of from 50 to 450.

Metal salts of phenols and sulfurised phenols are prepared by reactionwith an appropriate metal compound such as an oxide or hydroxide andneutral or overbased products may be obtained by methods well known inthe art.

Lubricating oil additives and intermediates of the present invention areoil-soluble or (in common with certain other additives referred tobelow) are dissolvable in oil with the aid of a suitable solvent, or arestably dispersible materials.

The present invention also provides for a lubricating oil compositionwhich comprises lubricating oil in a major amount and a minor amount ofan oil soluble sulfurised intermediate obtainable by the above process.

The present invention further provides for a lubricating oil concentratewhich comprises a minor amount of lubricating oil and a major amount ofan oil soluble sulfurised intermediate obtainable by the above process.

The present invention further provides for a low chlorine lubricatingoil composition comprising:

a) oil of lubricating viscosity;

b) one or more sulfurised intermediates or sulfurised additives with achlorine content of less than 1000 ppm; and

c) one or more ashless dispersants prepared from non-halogenatedpolymers, the chlorine content of the lubricating oil composition beingnot more than 100 ppm.

The present invention further also provides for a lubricating oilconcentrate comprising:

a) lubricating oil; and

b) at least one or more sulfurised intermediates or sulfurised additiveswith a chlorine content of less than 1000 ppm present in the concentrateat a level such that a low chlorine lubricating oil composition preparedfrom the concentrate comprises 100 ppm or less of chlorine.

It is preferred that the low chlorine lubricating oil compositioncomprises 50 ppm or less and most preferably 10 ppm or less e.g. 5 ppmor less of chlorine. It is preferred that the concentrate furthercomprises one or more ashless dispersants prepared from non-halogenatedpolymers.

Oil-soluble, dissolvable, or stably dispersible as that terminology isused herein does not necessarily indicate that the additives orintermediates are soluble, dissolvable, miscible, or capable of beingsuspended in oil in all proportions. It does mean, however, that theyare, for instance, soluble or stably dispersible in oil to an extentsufficient to exert their intended effect in the environment in whichthe oil is employed. Moreover, the additional incorporation of otheradditives may also permit incorporation of higher levels of a particularadditive or intermediate, if desired.

Additives and intermediates of the present invention as described hereincan be incorporated into the oil in any convenient way. Thus, they canbe added directly to the oil by dispersing or by dissolving them in theoil at the desired level of concentration, optionally with the aid of asuitable solvent such as, for example, toluene, cyclohexane, ortetrahydrofuran. In some cases blending may be effected at roomtemperature: in other cases elevated temperatures are advantageous suchas up to 100° C.

Base oils with which the additives and intermediates may be used includethose suitable for use in crankcase lubricating oils for spark-ignitedand compression-ignited internal combustion engines, for example,automobile and truck engines, marine and railroad diesel engines.

Synthetic base oils include alkyl esters of dicarboxylic acids,polyglycols and alcohols: poly-α-olefins, polybutenes, alkyl benzenes,organic esters of phosphoric acids and polysilicone oils.

Natural base oils include mineral lubricating oils which may vary widelyas to their crude source, for example, as to whether they areparaffinic, naphthenic, mixed, or paraffinic-naphthenic, as well as tothe method used in their production, for example, distillation range,straight run or cracked, hydrorefined, solvent extracted and the like.

More specifically, natural lubricating oil base stocks which can be usedmay be straight mineral lubricating oil or distillates derived fromparaffinic, naphthenic, asphaltic, or mixed base crude oils.Alternatively, if desired, various blended oils may be employed as wellas residual oils, particularly those from which asphaltic constituentshave been removed. The oils may be refined by any suitable method, forexample, using acid, alkali, and/or clay or other agents such, forexample, as aluminium chloride, or they may be extracted oils produced,for example, by solvent extraction with solvents, for example, phenol,sulfur dioxide, furfural, dichlorodiethylether, nitrobenzene, orcrotonaldehyde.

The lubricating oil base stock conveniently has a viscosity of about 2.5to about 12 cSt or mm²/sec and preferably about 3.5 to about 9 cSt ormm²/sec at 100° C.

Additives and intermediates of the present invention as described hereinmay be employed in a lubricating oil composition which compriseslubricating oil, typically in a major proportion, and the additives,typically in a minor proportion. Additional additives may beincorporated into the composition to enable it to meet particularrequirements. Examples of additives which may be included in lubricatingoil compositions are viscosity index improvers, corrosion inhibitors,oxidation inhibitors, friction modifiers, dispersants, detergents, metalrust inhibitors, anti-wear agents, pour point depressants, andanti-foaming agents.

The ashless dispersants comprise an oil soluble polymeric hydrocarbonbackbone having functional groups that are capable of associating withparticles to be dispersed. Typically, the dispersants comprise amine,alcohol, amide, or ester polar moieties attached to the polymer backboneoften via a bridging group. The ashless dispersant may be, for example,selected from oil soluble salts, esters, amino-esters, amides, imides,and oxazolines of long chain hydrocarbon substituted mono anddicarboxylic acids or their anhydrides; thiocarboxylate derivatives oflong chain hydrocarbons; long chain aliphatic hydrocarbons having apolyamine attached directly thereto; and Mannich condensation productsformed by condensing a long chain substituted phenol with formaldehydeand polyalkylene polyamine.

The oil soluble polymeric hydrocarbon backbone is typically an olefinpolymer or polyene, especially polymers comprising a major molar amount(i.e., greater than 50 mole %) of a C₂ to C₁₈ olefin (e.g., ethylene,propylene, butylene, isobutylene, pentene, octene-1, styrene), andtypically a C₂ to C₅ olefin. The oil soluble polymeric hydrocarbonbackbone may be a homopolymer (e.g., polypropylene or polyisobutylene)or a copolymer of two or more of such olefins (e.g., copolymers ofethylene and an alpha-olefin such as propylene or butylene, orcopolymers of two different alpha-olefins). Other copolymers includethose in which a minor molar amount of the copolymer monomers, e.g., 1to 10 mole %, is an α,ω-diene, such as a C₃ to C₂₂ non-conjugateddiolefin (e.g., a copolymer of isobutylene and butadiene, or a copolymerof ethylene, propylene and 1,4-hexadiene or 5-ethylidene-2-norbornene).Atactic propylene oligomer typically having {overscore (M)}_(n) of from700 to 5000 may also be used, as described in EP-A-490454, as well asheteropolymers such as polyepoxides.

One preferred class of olefin polymers is polybutenes and specificallypolyisobutenes (PIB) or poly-n-butenes, such as may be prepared bypolymerization of a C₄ refinery stream. Other preferred classes ofolefin polymers are ethylene alpha-olefin (EAO) copolymers andalpha-olefin homo- and copolymers having in each case a high degree(e.g., >30%) of terminal vinylidene unsaturation. That is, the polymerhas the following structure:

wherein P is the polymer chain and R is a C₁-C₁₈ alkyl group, typicallymethyl or ethyl. Preferably the polymers will have at least 50% of thepolymer chains with terminal vinylidene unsaturation. EAO copolymers ofthis type preferably contain 1 to 50 wt % ethylene, and more preferably5 to 48 wt % ethylene. Such polymers may contain more than onealpha-olefin and may contain one or more C₃ to C₂₂ diolefins. Alsousable are mixtures of EAO's of varying ethylene content. Differentpolymer types, e.g., EAO and PIB, may also be mixed or blended, as wellas polymers differing in {overscore (M)}_(n); components derived fromthese also may be mixed or blended.

Suitable olefin polymers and copolymers may be prepared by variouscatalytic polymerization processes. In one method, hydrocarbon feedstreams, typically C₃-C₅ monomers, are cationically polymerized in thepresence of a Lewis acid catalyst and, optionally, a catalytic promoter,e.g., an organoaluminum catalyst such as ethylaluminum dichloride and anoptional promoter such as HCl. Most commonly, polyisobutylene polymersare derived from Raffinate I refinery feedstreams. Various reactorconfigurations can be utilised, e.g., tubular or stirred tank reactors,as well as fixed bed catalyst systems in addition to homogeneouscatalysts. Such polymerization processes and catalysts are described,e.g., in U.S. Pat. Nos. 4,935,576; 4,952,739; 4,982,045; and UK-A2,001,662.

Conventional Ziegler-Natta polymerization processes may also be employedto provide olefin polymers suitable for use in preparing dispersants andother additives. However, preferred polymers may be prepared bypolymerising the appropriate monomers in the presence of a particulartype of Ziegler-Natta catalyst system comprising at least onemetallocene (e.g., a cyclopentadienyl-transition metal compound) and,preferably, a cocatalyst or an activator, e.g., an alumoxane compound oran ionising ionic activator such as tri (n-butyl) ammonium tetra(pentafluorophenyl) boron.

Metallocene catalysts are, for example, bulky ligand transition metalcompounds of the formula:

[L]_(m)M[A]_(n)

where L is a bulky ligand; A is a leaving group, M is a transition metaland m and n are such that the total ligand valency corresponds to thetransition metal valency. Preferably the catalyst is four co-ordinatesuch that the compound is ionizable to a 1⁺ valency state.

The ligands L and A may be bridged to each other, and if two ligands Aand/or L are present, they may be bridged. The metallocene compound maybe a full sandwich compound having two or more ligands L which may becyclopentadienyl ligands or cyclopentadienyl derived ligands, or theymay be half sandwich compounds having one such ligand L. The ligand maybe mono- or polynuclear or any other ligand capable of η-5 bonding tothe transition metal.

One or more of the ligands may π-bond to the transition metal atom,which may be a Group 4, 5 or 6 transition metal and/or a lanthanide oractinide transition metal, with zirconium, titanium and hafnium beingparticularly preferred.

The ligands may be substituted or unsubstituted, and mono-, di-, tri,tetra- and penta-substitution of the cyclopentadienyl ring is possible.Optionally the substituent(s) may act as one or more bridge between theligands and/or leaving groups and/or transition metal. Such bridgestypically comprise one or more of a carbon, germanium, silicon,phosphorus or nitrogen atom-containing radical, and preferably thebridge places a one atom link between the entities being bridged,although that atom may and often does carry other substituents.

The metallocene may also contain a further displaceable ligand,preferably displaced by a cocatalyst—a leaving group—that is usuallyselected from a wide variety of hydrocarbyl groups and halogens.

Such polymerizations, catalysts, and cocatalysts or activators aredescribed, for example, in U.S. Pat. Nos. 4,530,914; 4,665,208;4,808,561; 4,871,705; 4,897,455; 4,937,299; 4,952,716; 5,017,714;5,055,438; 5,057,475; 5,064,802; 5,096,867; 5,120,867; 5,124,418;5,153,157; 5,198,401; 5,227,440; 5,241,025; U.S. Ser. No. 992,690 (filedDec. 17, 1992; EP-A- 129,368; 277,003; 277,004; 420436; 520,732;WO91/04257; 92/00333; 93/08199 and 93/08221; and 94/07928.

The oil soluble polymeric hydrocarbon backbone will usually have anumber average molecular weight ({overscore (M)}_(n)) within the rangeof from 300 to 20,000. The {overscore (M)}_(n) of the polymer backboneis preferably within the range of 500 to 10,000, more preferably 700 to5,000 where its use is to prepare a component having the primaryfunction of dispersancy. Polymers of both relatively low molecularweight (e.g., {overscore (M)}_(n)=500 to 1500) and relatively highmolecular weight (e.g., {overscore (M)}_(n)=1500 to 5,000 or greater)are useful to make dispersants. Particularly useful olefin polymers foruse in dispersants have {overscore (M)}_(n) within the range of from1500 to 3000. Where the oil additive component is also intended to havea viscosity modifying effect it is desirable to use a polymer of highermolecular weight, typically with {overscore (M)}_(n) of from 2,000 to20,000; and if the component is intended to function primarily as aviscosity modifier then the molecular weight may be even higher, e.g.,{overscore (M)}_(n) of from 20,000 up to 500,000 or greater.Furthermore, the olefin polymers used to prepare dispersants preferablyhave approximately one double bond per polymer chain, preferably as aterminal double bond.

Polymer molecular weight, specifically {overscore (M)}_(n), can bedetermined by various known techniques. One convenient method is gelpermeation chromatography (GPC), which additionally provides molecularweight distribution information (see W. W. Yau, J. J. Kirkland and D. D.Bly, “Modern Size Exclusion Liquid Chromatography”, John Wiley and Sons,New York, 1979). Another useful method, particularly for lower molecularweight polymers, is vapour pressure osmometry (see, e.g., ASTM D3592).

The oil soluble polymeric hydrocarbon backbone may be functionalized toincorporate a functional group into the backbone of the polymer, or asone or more groups pendant from the polymer backbone. The functionalgroup typically will be polar and contain one or more hetero atoms suchas P, O, S, N, halogen, or boron. It can be attached to a saturatedhydrocarbon part of the oil soluble polymeric hydrocarbon backbone viasubstitution reactions or to an olefinic portion via addition orcycloaddition reactions. Alternatively, the functional group can beincorporated into the polymer in conjunction with oxidation or cleavageof the polymer chain end (e.g., as in ozonolysis).

Useful functionalization reactions include: halogenation of the polymerat an olefinic bond and subsequent reaction of the halogenated polymerwith an ethylenically unsaturated functional compound (e.g., maleationwhere the polymer is reacted with maleic acid or anhydride); reaction ofthe polymer with an unsaturated functional compound by the “ene”reaction absent halogenation; reaction of the polymer with at least onephenol group (this permits derivatization in a Mannich base-typecondensation); reaction of the polymer at a point of unsaturation withcarbon monoxide using a Koch-type reaction to introduce a carbonyl groupin an iso or neo position; reaction of the polymer with thefunctionalizing compound by free radical addition using a free radicalcatalyst; reaction with a thiocarboxylic acid derivative; and reactionof the polymer by air oxidation methods, epoxidation, chloroamination,or ozonolysis. It is preferred that the polymer is not halogenated.

The functionalized oil soluble polymeric hydrocarbon backbone is thenfurther derivatized with a nucleophilic reactant such as an amine,amino-alcohol, alcohol, metal compound or mixture thereof to form acorresponding derivative.

Useful amine compounds for derivatizing functionalized polymers compriseat least one amine and can comprise one or more additional amine orother reactive or polar groups. These amines may be hydrocarbyl aminesor may be predominantly hydrocarbyl amines in which the hydrocarbylgroup includes other groups, e.g., hydroxy groups, alkoxy groups, amidegroups, nitriles, imidazoline groups, and the like. Particularly usefulamine compounds include mono-and polyamines, e.g., polyalkylene andpolyoxyalklene polyamines of about 2 to 60, conveniently 2 to 40 (e.g.,3 to 20), total carbon atoms and about 1 to 12, conveniently 3 to 12,and preferably 3 to 9 nitrogen atoms in the molecule. Mixtures of aminecompounds may advantageously be used such as those prepared by reactionof alkylene dihalide with ammonia. Preferred amines are aliphaticsaturated amines, including, e.g., 1,2-diaminoethane;1,3-diaminopropane; 1,4-diaminobutane; 1,6-diaminohexane; polyethyleneamines such as diethylene triamine; triethylene tetramine; tetraethylenepentamine; and polypropyleneamines such as 1,2-propylene diamine; anddi-(1,2-propylene)triamine.

Other useful amine compounds include: alicyclic diamines such as1,4-di(aminomethyl) cyclohexane, and heterocyclic nitrogen compoundssuch as imidazolines. A particularly useful class of amines are thepolyamido and related amido-amines as disclosed in U.S. Pat. Nos.4,857,217; 4,956,107; 4,963,275; and 5,229,022. Also usable istris(hydroxymethyl)amino methane (THAM) as described in U.S. Pat. Nos.4,102,798; 4,113,639; 4,116,876; and UK 989,409. Dendrimers, star-likeamines, and comb-structure amines may also be used. Similarly, one mayuse the condensed amines disclosed in U.S. Pat. No. 5,053,152. Thefunctionalized polymer is reacted with the amine compound according toconventional techniques as described in EP-A 208,560; U.S. Pat. No.4,234,435 and U.S. Pat. No. 5,229,022.

The functionalized oil soluble polymeric hydrocarbon backbones also maybe derivatized with hydroxy compounds such as monohydric and polyhydricalcohols or with aromatic compounds such as phenols and naphthols.Polyhydric alcohols are preferred, e.g., alkylene glycols in which thealkylene radical contains from 2 to 8 carbon atoms. Other usefulpolyhydric alcohols include glycerol, mono-oleate of glycerol,monostearate of glycerol, monomethyl ether of glycerol, pentaerythritol,dipentaerythritol, and mixtures thereof. An ester dispersant may also bederived from unsaturated alcohols such as allyl alcohol, cinnamylalcohol, propargyl alcohol, 1-cyclohexane-3-ol, and oleyl alcohol. Stillother classes of the alcohols capable of yielding ashless dispersantscomprise the ether-alcohols and including, for example, theoxy-alkylene, oxy-arylene. They are exemplified by ether-alcohols havingup to 150 oxy-alkylene radicals in which the alkylene radical containsfrom 1 to 8 carbon atoms. The ester dispersants may be di-esters ofsuccinic acids or acidic esters, i.e., partially esterified succinicacids; as well as partially esterified polyhydric alcohols or phenols,i.e., esters having free alcohols or phenolic hydroxyl radicals. Anester dispersant may be prepared by one of several known methods asillustrated, for example, in U.S. Pat. No. 3,381,022.

A preferred group of ashless dispersants includes those derived frompolyisobutylene substituted with succinic anhydride groups and reactedwith polyethylene amines (e.g., tetraethylene pentamine, pentaethylene(di)(pent)amine(?), polyoxypropylene diamine) aminoalcohols such astrismethylolaminomethane and optionally additional reactants such asalcohols and reactive metals e.g., pentaerythritol, and combinationsthereof. Also useful are dispersants wherein a polyamine is attacheddirectly to the long chain aliphatic hydrocarbon as shown in U.S. Pat.Nos. 3,275,554 and 3,565,804 where a halogen group on a halogenatedhydrocarbon is displaced with various alkylene polyamines.

Another class of ashless dispersants comprises Mannich base condensationproducts. Generally, these are prepared by condensing about one mole ofan alkyl-substituted mono- or polyhydroxy benzene with about 1 to 2.5moles of carbonyl compounds (e.g., formaldehyde and paraformaldehyde)and about 0.5 to 2 moles polyalkylene polyamine as disclosed, forexample, in U.S. Pat. No. 3,442,808. Such Mannich condensation productsmay include a long chain, high molecular weight hydrocarbon (e.g.,{overscore (M)}_(n) of 1,500 or greater) on the benzene group or may bereacted with a compound containing such a hydrocarbon, for example,polyalkenyl succinic anhydride, as shown in U.S. Pat. No. 3,442,808.

Examples of functionalized and/or derivatized olefin polymers based onpolymers synthesized using metallocene catalyst systems are described inU.S. Pat. Nos. 5,128,056; 5,151,204; 5,200,103; 5,225,092; 5,266,223;U.S. Ser. No. 992,192 (filed Dec. 17, 1992); U.S. Ser. No. 992,403(filed Dec. 17, 1992); U.S. Ser. No. 070,752 (filed Jun. 2, 1993);EP-A-440,506; 513,157; 513,211. The functionalization and/orderivatizations and/or post treatments described in the followingpatents may also be adapted to functionalize and/or derivatize thepreferred polymers described above: U.S. Pat. Nos. 3,087,936; 3,254,025;3,275,554; 3,442,808, and 3,565,804.

The dispersant can be further post-treated by a variety of conventionalpost treatments such as boration, as generally taught in U.S. Pat. Nos.3,087,936 and 3,254,025. This is readily accomplished by treating anacyl nitrogen-containing dispersant with a boron compound selected fromthe group consisting of boron oxide, boron halides, boron acids andesters of boron acids, in an amount to provide from about 0.1 atomicproportion of boron for each mole of the acylated nitrogen compositionto about 20 atomic proportions of boron for each atomic proportion ofnitrogen of the acylated nitrogen composition. Usefully the dispersantscontain from about 0.05 to 2.0 wt. %, e.g. 0.05 to 0.7 wt. % boron basedon the total weight of the borated acyl nitrogen compound. The boron,which appears be in the product as dehydrated boric acid polymers(primarily (HBO₂)₃), is believed to attach to the dispersant imides anddiimides as amine salts e.g., the metaborate salt of the diimide.Boration is readily carried out by adding from about 0.05 to 4, e.g., 1to 3 wt. % (based on the weight of acyl nitrogen compound) of a boroncompound, preferably boric acid, usually as a slurry, to the acylnitrogen compound and heating with stirring at from 135° to 190° C.,e.g., 140°-170° C., for from 1 to 5 hours followed by nitrogenstripping. Alternatively, the boron treatment can be carried out byadding boric acid to a hot reaction mixture of the dicarboxylic acidmaterial and amine while removing water.

Viscosity modifiers (or viscosity index improvers) impart high and lowtemperature operability to a lubricating oil. Viscosity modifiers thatalso function as dispersants are also known and may be prepared asdescribed above for ashless dispersants. In general, these dispersantviscosity modifiers are functionalized polymers (e.g. inter polymers ofethylene-propylene post grafted with an active monomer such as maleicanhydride) which are then derivatized with, for example, an alcohol oramine.

The lubricant may be formulated with or without a conventional viscositymodifier and with or without a dispersant viscosity modifier. Suitablecompounds for use as viscosity modifiers are generally high molecularweight hydrocarbon polymers, including polyesters. Oil soluble viscositymodifying polymers generally have weight average molecular weights offrom about 10,000 to 1,000,000, preferably 20,000 to 500,000, which maybe determined by gel permeation chromatography (as described above) orby light scattering.

Representative examples of suitable viscosity modifiers arepolyisobutylene, copolymers of ethylene and propylene and higheralpha-olefins, polymethacrylates, polyalkylmethacrylates, methacrylatecopolymers, copolymers of an unsaturated dicarboxylic acid and a vinylcompound, inter polymers of styrene and acrylic esters, and partiallyhydrogenated copolymers of styrene/isoprene, styrene/butadiene, andisoprene/butadiene, as well as the partially hydrogenated homopolymersof butadiene and isoprene and isoprene/divinylbenzene.

Metal-containing or ash-forming detergents function both as detergentsto reduce or remove deposits and as acid neutralisers or rustinhibitors, thereby reducing wear and corrosion and extending enginelife. Detergents generally comprise a polar head with a long hydrophobictail, with the polar head comprising a metal salt of an acidic organiccompound. The salts may contain a substantially stoichiometric amount ofthe metal in which case they are usually described as normal or neutralsalts, and would typically have a total base number or TBN (as may bemeasured by ASTM D2896) of from 0 to 80. It is possible to include largeamounts of a metal base by reacting an excess of a metal compound suchas an oxide or hydroxide with an acidic gas such as carbon dioxide. Theresulting overbased detergent comprises neutralised detergent as theouter layer of a metal base (e.g. carbonate) micelle. Such overbaseddetergents may have a TBN of 150 or greater, and typically of from 250to 450 or more.

Detergents that may be used include oil-soluble neutral and overbasedsulfonates, phenates, sulfurized phenates, thiophosphonates,salicylates, and naphthenates and other oil-soluble carboxylates of ametal, particularly the alkali or alkaline earth metals, e.g., sodium,potassium, lithium, calcium, and magnesium. The most commonly usedmetals are calcium and magnesium, which may both be present indetergents used in a lubricant, and mixtures of calcium and/or magnesiumwith sodium. Particularly convenient metal detergents are neutral andoverbased calcium sulfonates having TBN of from 20 to 450 TBN, andneutral and overbased calcium phenates and sulfurized phenates havingTBN of from 50 to 450.

Sulfonates may be prepared from sulfonic acids which are typicallyobtained by the sulfonation of alkyl substituted aromatic hydrocarbonssuch as those obtained from the fractionation of petroleum or by thealkylation of aromatic hydrocarbons. Examples included those obtained byalkylating benzene, toluene, xylene, naphthalene, diphenyl or theirhalogen derivatives such as chlorobenzene, chlorotoluene andchloronaphthalene. The alkylation may be carried out in the presence ofa catalyst with alkylating agents having from about 3 to more than 70carbon atoms. The alkaryl sulfonates usually contain from about 9 toabout 80 or more carbon atoms, preferably from about 16 to about 60carbon atoms per alkyl substituted aromatic moiety.

The oil soluble sulfonates or alkaryl sulfonic acids may be neutralizedwith oxides, hydroxides, alkoxides, carbonates, carboxylate, sulfides,hydrosulfides, nitrates, borates and ethers of the metal. The amount ofmetal compound is chosen having regard to the desired TBN of the finalproduct but typically ranges from about 100 to 220 wt % (preferably atleast 125 wt %).

Dihydrocarbyl dithiophosphate metal salts are frequently used asanti-wear and antioxidant agents. The metal may be an alkali or alkalineearth metal, or aluminum, lead, tin, molybdenum, manganese, nickel orcopper. The zinc salts are most commonly used in lubricating oil inamounts of 0.1 to 10, preferably 0.2 to 2 wt. %, based upon the totalweight of the lubricating oil composition. They may be prepared inaccordance with known techniques by first forming a dihydrocarbyldithiophosphoric acid (DDPA), usually by reaction of one or more alcoholor a phenol with P₂S₅ and then neutralising the formed DDPA with a zinccompound. The zinc dihydrocarbyl dithiophosphates can be made from mixedDDPA which in turn may be made from mixed alcohols. Alternatively,multiple zinc dihydrocarbyl dithiophosphates can be made andsubsequently mixed.

Thus the dithiophosphoric acid containing secondary hydrocarbyl groupsused in this invention may be made by reacting mixtures of primary andsecondary alcohols. Alternatively, multiple dithiophosphoric acids canbe prepared where the hydrocarbyl groups on one are entirely secondaryin character and the hydrocarbyl groups on the others are entirelyprimary in character. To make the zinc salt any basic or neutral zinccompound could be used but the oxides, hydroxides and carbonates aremost generally employed. Commercial additives frequently contain anexcess of zinc due to use of an excess of the basic zinc compound in theneutralisation reaction.

The preferred zinc dihydrocarbyl dithiophosphates useful in the presentinvention are oil soluble salts of dihydrocarbyl dithiophosphoric acidsand may be represented by the following formula:

wherein R and R′ may be the same or different hydrocarbyl radicalscontaining from 1 to 18, preferably 2 to 12, carbon atoms and includingradicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl andcycloaliphatic radicals. Particularly preferred as R and R′ groups arealkyl groups of 2 to 8 carbon atoms. Thus, the radicals may, forexample, be ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl,amyl, n-hexyl, i-hexyl, n-octyl, decyl, dodecyl, octadecyl,2-ethylhexyl, phenyl, butylphenyl, cyclohexyl, methylcyclopentyl,propenyl, butenyl. In order to obtain oil solubility, the total numberof carbon atoms (i.e. R and R′) in the dithiophosphoric acid willgenerally be about 5 or greater. The zinc dihydrocarbyl dithiophosphatecan therefore comprise zinc dialkyl dithiophosphates. At least 50 (mole)% of the alcohols used to introduce hydrocarbyl groups into thedithiophosphoric acids are secondary alcohols.

Additional additives are typically incorporated into the compositions ofthe present invention. Examples of such additives are antioxidants,anti-wear agents, friction modifiers, rust inhibitors, anti-foamingagents, demulsifiers, and pour point depressants.

Oxidation inhibitors or antioxidants reduce the tendency of mineral oilsto deteriorate in service which deterioration can be evidenced by theproducts of oxidation such as sludge and varnish-like deposits on themetal surfaces and by viscosity growth. Such oxidation inhibitorsinclude hindered phenols, alkaline earth metal salts ofalkylphenolthioesters having preferably C₅ to C₁₂ alkyl side chains,calcium nonylphenol sulfide, ashless oil soluble phenates and sulfurizedphenates, phosphosulfurized or sulfurized hydrocarbons, phosphorousesters, metal thiocarbamates, oil soluble copper compounds as describedin U.S. Pat. No. 4,867,890, and molybdenum containing compounds.Examples of molybdenum compounds include molybdenum salts of inorganicand organic acids (see, for example, U.S. Pat. No. 4,705,641),particularly molybdenum salts of monocarboxylic acids having from 1 to50, preferably 8 to 18, carbon atoms, for example, molybdenum octoate(2-ethyl hexanoate), naphthenate or stearate; overbasedmolybdenum-containing complexes as disclosed in EP 404 650A; molybdenumdithiocarbamates and molybdenum dithiophosphates; oil-soluble molybdenumxanthates and thioxanthates as disclosed in U.S. Pat. Nos. 4,995,996 and4,966,719; oil-soluble molybdenum- and sulfur-containing complexes; andaromatic amines, preferably having at least two aromatic groups attacheddirectly to the nitrogen.

Typical oil soluble aromatic amines having at least two aromatic groupsattached directly to one amine nitrogen contain from 6 to 16 carbonatoms. The amines may contain more than two aromatic groups. Compoundshaving a total of at least three aromatic groups in which two aromaticgroups are linked by a covalent bond or by an atom or group (e.g., anoxygen or sulfur atom, or a —CO—, —SO₂— or alkylene group) and two aredirectly attached to one amine nitrogen also considered aromatic amineshaving at least two aromatic groups attached directly to the nitrogen.The aromatic rings are typically substituted by one or more substituentsselected from alkyl, cycloalkyl, alkoxy, aryloxy, acyl, acylamino,hydroxy, and nitro groups.

Friction modifiers may be included to improve fuel economy. In additionto the oil soluble aliphatic, oxyalkyl, or arylalkyl amines describedabove to add nitrogenous TBN, other friction modifiers are known, Amongthese are esters formed by reacting carboxylic acids and anhydrides withalkanols. Other conventional friction modifiers generally consist of apolar terminal group (e.g. carboxyl or hydroxyl) covalently bonded to anoleophillic hydrocarbon chain. Esters of carboxylic acids and anhydrideswith alkanols are described in U.S. Pat. No. 4,702,850. Examples ofother conventional friction modifiers are described by M. Belzer in the“Journal of Tribology” (1992), Vol. 114, pp. 675-682 and M. Belzer andS. Jahanmir in “Lubrication Science” (1988), Vol. 1, pp. 3-26.

Rust inhibitors selected from the group consisting of nonionicpolyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, andanionic alkyl sulfonic acids may be used. When the formulation of thepresent invention is used, these anti-rust inhibitors are not generallyrequired.

Copper and lead bearing corrosion inhibitors may be used, but aretypically not required with the formulation of the present invention.Typically such compounds are the thiadiazole polysulfides containingfrom 5 to 50 carbon atoms, their derivatives and polymers thereof.Derivatives of 1,3,4 thiadiazoles such as those described in U.S. Pat.Nos. 2,719,125; 2,719,126; and 3,087,932; are typical. Other similarmaterials are described in U.S. Pat. Nos. 3,821,236; 3,904,537;4,097,387; 4,107,059; 4,136,043; 4,188,299; and 4,193,882. Otheradditives are the thio and polythio sulfenamides of thiadiazoles such asthose described in UK. Patent Specification No. 1,560,830.Benzotriazoles derivatives also fall within this class of additives.When these compounds are included in the lubricating composition, theyare preferably present in an amount not exceeding 0.2 wt % activeingredient.

A small amount of a demulsifying component may be used. A preferreddemulsifying component is described in EP 330,522. It is obtained byreacting an alkylene oxide with an adduct obtained by reacting abis-epoxide with a polyhydric alcohol. The demulsifier should be used ata level not exceeding 0.1 mass % active ingredient. A treat rate of0.001 to 0.05 mass % active ingredient is convenient.

Pour point depressants, otherwise known as lube oil flow improvers,lower the minimum temperature at which the fluid will flow or can bepoured. Such additives are well known. Typical of those additives whichimprove the low temperature fluidity of the fluid are C₈ to C₁₈ dialkylfumarate/vinyl acetate copolymers and polyalkylmethacrylates.

Foam control can be provided by many compounds including an antifoamantof the polysiloxane type, for example, silicone oil or polydimethylsiloxane.

Some of the above-mentioned additives can provide a multiplicity ofeffects; thus for example, a single additive may act as adispersant-oxidation inhibitor. This approach is well known and does notrequire further elaboration.

When lubricating compositions contain one or more of the above-mentionedadditives, each additive is typically blended into the base oil in anamount which enables the additive to provide its desired function.Representative effective amounts of such additives, when used incrankcase lubricants, are listed below. All the values listed are statedas mass percent active ingredient.

MASS % MASS % ADDITIVE (Broad) (Preferred) Ashless Dispersant 0.1-20 1-8 Metal detergents 0.1-6  0.2-4  Corrosion Inhibitor  0-5   0-1.5Metal dihydrocarbyl dithiophosphate 0.1-6  0.1-4  Supplementalanti-oxidant  0-5 0.01-1.5 Pour Point Depressant 0.01-5  0.01-1.5Anti-Foaming Agent  0-5 0.001-0.15 Supplemental Anti-wear Agents  0-0.5  0-0.2 Friction Modifier  0-5   0-1.5 Viscosity Modifier¹ 0.01-6   0-4Mineral or Synthetic Base Oil Balance Balance ¹Viscosity modifiers areused only in multi-graded oils.

For non-crankcase applications, the quantities andlor proportions of theabove additives may be varied; for example, marine diesel cylinderlubricants use relatively higher amounts of metal detergents, which mayform 10-50 wt % of the lubricant.

The components may be incorporated into a base oil in any convenientway. Thus, each of the components can be added directly to the oil bydispersing or dissolving it in the oil at the desired level ofconcentration. Such blending may occur at ambient temperature or at anelevated temperature.

Preferably all the additives except for the viscosity modifier and thepour point depressant are blended into a concentrate or additivepackage, that is subsequently blended into basestock to make finishedlubricant. Use of such concentrates is conventional. The concentratewill typically be formulated to contain the additive(s) in properamounts to provide the desired concentration in the final formulationwhen the concentrate is combined with a predetermined amount of baselubricant.

Preferably the concentrate is made in accordance with the methoddescribed in U.S. Pat. No. 4,938,880. That patent describes making apremix of ashless dispersant and metal detergents that is pre-blended ata temperature of at least about 100° C. Thereafter the pre-mix is cooledto at least 85° C. and the additional components are added.

The final formulations may employ from 2 to 15 mass % and preferably 5to 10 mass %, typically about 7 to 8 mass % of the concentrate oradditive package with the remainder being base oil.

The invention will now be described by of illustration only withreference to the following examples. In the examples, unless otherwisenoted, all treat rates of all additives are reported as mass percentactive ingredient.

Preparation of Sulfurised Intermediates

This following is the method used to prepare sulfurised intermediates.

Sulfur monochloride (270.1 g; 2 moles) was added to a reaction vesselcontaining 1040 g (4.11 moles) of a nonyl phenol (Phenol 1) being amixture of dinonyl phenol and nonylphenol (35:65 wt %) and having anaverage molecular weight of 253. This addition was made over a period of3 hours and 45 minutes. The reaction mixture was stirred efficientlyduring the addition and the temperature was ramped from 60° C. to 90° C.When the addition of sulfur monochloride was completed the temperaturewas raised to 110° C. and held at this temperature for 2 hours whilstthe reaction mixture was purged with nitrogen at a rate of 200 cm³min⁻¹.

This procedure was repeated using various amounts of sulfur monochlorideand/or replacing the phenol with 1040 g (3.388 moles) of a nonyl phenol(Phenol 2) being a mixture of dinonyl phenol and nonyl phenol (80:20 wt%) and having an average molecular weight of 307. The sulfur content,active sulfur content, chlorine content and kinematic viscosities of theresultant products are given in Table 1.

TABLE 1 Reaction Materials Product Properties Phenol: S Active ExampleS₂Cl₂ S₂Cl₂ Mass Cl kV sulfur No Phenol g Moles % ppm cSt mass %  1 1164.8 3.368 6.84 400 20 1.02  2 1 190.3 2.917 7.82 400 25 1.31  3 1216.3 2.566 8.84 400 31 1.40  4 1 242.9 2.285 9.58 400 40 1.64  5 1242.9 2.285 9.65 500 42 —  6 1 242.9 2.285 9.75 600 43 —  7 1 242.92.285 9.80 400 41 1.93  8 1 270.1 2.055 10.73 500 57 —  9 1 270.1 2.05510.94 600 — — 10 1 309.2 1.795 12.18 800 103 2.43 Comp 1 1 340.7 1.62913.22 1200 187 2.63 Comp 2 1 378.5 1.466 14.40 2000 407 3.42 Comp 3 1400.1 1.387 15.57 2900 702 — 11 2 200.1 2.286 8.16 600 — — 12 2 200.12.286 8.53 500 — — 13 2 222.5 2.029 9.14 800 89 — Comp 4 2 254.7 1.79610.36 2100 149 — Comp 5 2 280.7 1.630 11.26 5900 198 — Comp 6 2 317.11.443 12.24 11400 255 — Comp 7 2 329.6 1.388 12.79 14100 268 — Comp 8 2329.6 1.388 12.87 13400 268 —

Examples 1 to 13 are examples of intermediates of the present invention.these examples all have chlorine levels of less than 1000 ppm andkinematic viscosities of less than 100 cSt at 100° C. whereas thecomparative examples 1 to 8 have chlorine levels of 1200 ppm or greaterand higher kinematic viscosities.

With reference to the use of phenol 1 (average molecular weight 253) thedata illustrates that reactions using a mole ratio of phenol to sulfurmonochloride of 1.795 or greater produce intermediate products with lowchlorine and acceptable sulfur levels. With phenol 2 (average molecularweight 307) ratios of 2.0 or more give good results.

EXAMPLE 14

The general procedure outlined above was repeated with the exceptionthat 8000 g (31.62 moles) of nonyl phenol (Phenol 1) and, 2078 g (15.374moles) of sulfur monochloride was used (mole ratio of phenol to sulfurmonochloride of 2.057). The addition time was 2 hours and 30 minutes,the temperature was ramped from 60° C. to 105° C. during the addition ofsulfur monochloride and the nitrogen purge was 1.2 I min⁻¹. Theresulting product had a sulfur content of 10.99 wt %, a chlorine contentof 600 ppm and a kinematic viscosity at 100° C. of 59 cS or mm² sec⁻¹.

Preparation of Additives by Olefin Treatment

The following is the general method used to prepare additives of thepresent invention by reaction of an active sulfur containing sulfurisedphenol intermediate with an olefin or acetylenic compound.

The intermediate of Example 7 (97.5 g) was charged to a stirred reactionvessel along with 7.5 g of a borated ashless dispersant (being acommercially available polyisobutenyl succinimide) as a catalyst(Catalyst 1), 45.0 g of SN150 NL as diluent oil and 37.05 g (olefinratio mass % of 38) of geraniol a di-olefin. The temperature of thereaction mixture was raised to 150° C. over a period of 1 hour and thereaction mixture was held at this temperature for 6 hours after which avacuum was applied to remove excess olefin over a period of 2 hours.After vacuum stripping the resultant product was diluted with SN150NLoil to give an active ingredient in respect of sulfurised phenol of 65mass %. The resultant product had <0.1% free geraniol

This procedure was repeated for a number of different olefins, withphenyl acetylene, with varying amounts of olefin reaction times,reaction temperatures and with various catalysts. Each product wastested for its seals performance using the following procedure. Theresults are in Tables 3 and 4.

Test Method for Seals Performance

The effect of the additive compositions on nitrile seals was tested byimmersing samples of a nitrile elastomer in a lubricating oilcomposition containing a proprietary package of additives and theadditive to be tested, and comparing the elongation at break (EAB)and/or tensile strength (TS) of the samples after immersion with thecorresponding figures before immersion. The most effective additives arethose giving the smallest percentage loss in the elongation at breakand/or tensile strength. Test Methods DIN 53521 and DIN 53504 were used.

Panel Coker Performance

Two additives prepared according to the general method described aboveusing a sulfurised phenol and either geraniol or tetramer were added toa proprietary lubricating oil formulation containing conventionaladditives and tested in the Panel Coker Test. For comparison purposes anadditive was prepared using polybutadiene without removal of the excessolefin used in the reaction. The data is presented in Table 2.

TABLE 2 Panel Coker Additives Treat Mass % Average Olefin Stripped (a.i.Mass %) Merit A Geraniol Y 3.0 (1.625) 7.18 B Tetramer Y 2.8 (1.625)8.63 C Polybutadiene N 3.0 (1.625) 1.12

These results show that additive C, which was unstripped, hassignificantly poorer Panel Coker performance when compared to additivesA and B prepared according to the present invention.

TABLE 3 Treat Materials and conditions Seals Test Olefin Catalyst atProduct Ex Ratio 8% mass treat Delta Delta No Olefin Mass % (5) ratio(5) Stripped Mass % TS % EAB %  7 none — — — 1.1 −63 −69 15 none — — —1.1 −67 −69 16 none — — — 1.1 −55 −65 Comp 9 geraniol 38 Catalyst 1 N1.1 −1 −15 17 geraniol 38 Catalyst 1 Y 1.4 −1 −14 18 geraniol 38Catalyst 1 Y 2.6 −2 −16 3.8 −1 −15 19 geraniol 26 Catalyst 1 Y 1.3 −18A2 2.5 −18 −37 20 geraniol 15 Catalyst 1 Y 1.2 −22 A5 2.4 −26 46 21geraniol 5 Catalyst 1 Y 1.1 46 −61 2.3 −63 −68 22 1,5-COD(3) 38 Catalyst1 Y 1.2 −12 −37 23 tetramer 77 DETA(4) Y 1.1 −18 41 24 tetramer 77octylamine Y 1.1 −14 42 25 DCP(1) 33 Catalyst 1 Y 1.2 −16 −39 26 styrene52 Catalyst 1 Y 1.2 −18 −50 27 PAC(2) 25 Catalyst 1 Y 1.3 −8 −36 1dicyclopentadiene 2 phenylacetylene 3 1,5-cyclooctadiene 4 diethylenetetramine 5 to intermediate 6 C₁₂ Propylene Tetramer

There are a number of aspects illustrated by the results shown in Table3.

Example 18 to 21 illustrate, in the case of geraniol, the effect on sealcompatibility of the reaction with various amounts of olefin; the largerthe excess of olefin (olefin ratio) the better the seal compatibility ofthe resultant additive.

Examples 22 to 27 illustrate that acetylenic compounds and olefins otherthan geraniol can be used to prepare seal compatible additives. Examples23 and 24 also illustrate that different catalysts can be used in theolefin treatment process.

Examples 18, 19 and 20 also illustrate that additives reacted witholefin by this process can be used at high treat rates without having anadverse impact on the seal compatibility.

There are a number of aspects illustrated by the results shown in Table4. Firstly the results illustrate in the case of 1,5-cyclooctadiene thatreaction temperature and reaction time have an effect on sealcompatibility. Comparative Example 11 shows that there has only been aminor improvement in seal compatibility when the reaction with olefin isundertaken for a short period of time (2 hours) at a relatively lowtemperature (100° C.). The other examples in Table 4 illustrate thatseal compatibility improves with increasing reaction temperature andwith increasing reaction time.

TABLE 4 Treat Materials and Conditions Olefin Seals Test Ratio Treat ExMass Time Temp Mass Delta Delta No Phenol Olefin % (5) hrs ° C. Stripped% TS % EAB %  7 1 none — — — — 1.1 −63 −69 Comp 10 1 1,5-COD 38 2 100 N1.4 −18 48 Comp 11 1 1,5-COD 38 2 100 Y 1.1 −62 −68 28 1 1,5-COD 38 2150 Y 1.1 −24 44 29 1 1,5-COD 38 6 120 Y 1.1 −57 −64 30 1 1,5-COD 38 6130 Y 1.1 −31 45 31 1 1,5-COD 38 6 140 Y 1.2 −21 −41 12 2 none — — — —1.1 −55 −65 32 1 Tetramer 41 6 245 Y 1.1 −6 −34 33 2 Tetramer 77 60 150Y 1.4 −11 −39

Tetramer=C₁₂ Propylene Tetramer; a commercially available material fromExxon Chemical.

EXAMPLES 34 to 39

A further group of additives were prepared using different reactiontimes as follows using a sulfurised intermediate (A) which was preparedby the general method described above and was found to have a sulfurcontent of 9.74 wt % and a chlorine content of 900 ppm.

Olefin treatment was carried out using this intermediate (A), tetramer(B) as olefin, an ashless dispersant (being a commercially availablepolyisobutenyl succinimide) as a catalyst (C) and SN150 NL as diluentoil. The temperature of the reaction mixture was raised to 200° C. overa period of 1 hour and the reaction mixture was held at this temperaturefor between 0.5 and 8 hours after which a vacuum was applied to removeexcess olefin over a period of 2 hours and at a temperature of 150° C.After vacuum stripping the resultant product was diluted with SN150NLoil to give an active ingredient in respect of sulfurised phenol of 65mass %. Each additive was tested for its seal compatibility using theabove method; the results are given in Table 5. The results illustratethat increasing the reaction time results in improvements in sealcompatibility of the resultant additives. Also Examples 34 and 39illustrate that the olefin treatment results in an additive productwhich has a lower chlorine content compared with the untreatedintermediate even taking into account the dilution with oil to give a 65mass % product. The results also illustrate that longer reaction timesresult in a greater reduction in chlorine content.

TABLE 5 Product Reactants/Conditions properties Seals Test Ex A Oil C BTime % Cl Treat Delta Delta No g g g g hrs Free B ppm Mass % TS % EAB %34 70.7 32.6 5.4 14.5 0.5 0.2 300 1.1 −22.1 −42.8 35 66.2 30.6 5.1 13.61 — — 1.1 −12.3 −33.8 36 67.7 31.3 5.2 13.9 2 — — 1.1 −9.3 −30.9 37 6329.5 4.9 13.1 4 — — 1.1 −7.2 −29.4 38 71.3 32.9 5.5 14.6 6 — — 1.1 −7.0−29.4 39 85.9 39.6 6.6 17.6 8 0.7 100 1.1 4.9 −28.6

EXAMPLE 40

A further additive was prepared from the intermediate used in Examples34 to 39 as follows;

A reaction mixture consisting of intermediate A (65.4 g), 5.0 g of aborated ashless dispersant (being a commercially availablepolyisobutenyl succinimide) as a catalyst (Catalyst 1), 30.2 g of SN150NL as diluent oil and 13.5 g of tetramer as the olefin was charged to astirred reaction vessel. The temperature of the reaction mixture wasraised to 215° C. over a period of 1 hour and the reaction mixture washeld at this temperature for 8 hours after which a vacuum was applied toremove excess olefin over a period of 2 hours and at a temperature of150° C. After vacuum stripping the resultant product was diluted withSN150NL oil to give an active ingredient in respect of sulfurised phenolof 65 mass %. The resultant product had a sulfur content of 4.1 wt %, afree olefin content of <0.9 wt % and a chlorine content of <100 ppm.Also when tested at a treat rate of 1.1 mass % the additive product hada Delta TS % of −9.9 and a Delta EAB % of −41.5.

EXAMPLE 41

An additive of the present invention was also tested for its performancein the VWInTD engine test which is undertaken with a Volkswagen 1.6Intercooled Turbocharged diesel engine and run according to the industrystandard CEC L46-T-93 procedure. New pistons were used at the start ofeach test and the piston cleanliness following each test rated visuallyaccording to standard procedure DIN 51 361, part 2 and recorded as‘piston merits’ on a numerical scale of from 0 to 100, with a highernumerical value corresponding to a lower level of piston deposits. Thetest is typically used as a “pass/fail” performance test, whereby alubricating oil composition must achieve at least 70 piston merits to beconsidered a “pass” for diesel piston cleanliness. The additive preparedaccording to the present invention was compared to a commerciallyavailable diphenylamine antioxidant in a formulation which comprised aproprietary additive package including a multifunctional VI, adispersant, a detergent mixture, a ZDDP, other antioxidants, an antifoamand a demulsifier, in base oil.

The results of these tests are presented in Table 6 and clearly show thesuperior ring stick mance of the additive of the present invention.

TABLE 6 ASF Ring Additive wt % Piston merits Stick Example 41 Tetramertreated 1.5 67.8 0.0 intermediate Comp Ex 12 Diphenylamine 1.5 59.0 5.0

EXAMPLE 42

An additive of the present invention was also tested for its performancein the Sequence IIIE engine test which is undertaken to evaluate thehigh-speed, high-temperature oxidation, wear and deposit-formingtendencies of motor oils for gasoline engines. The test procedure is asgiven in ASTM STP 315. The additive of the present invention wascompared to a commercially available sulfurised phenolic additive whichhad a higher sulfur content than the additive of the present inventionand a higher chlorine content. These additives were compared in aformulation which comprised a proprietary additive package including aviscosity modifier, a dispersant, a detergent mixture, a ZDDP, and otherantioxidants, in base oil. The results of these tests are presented inTable 7 and clearly show the superior antioxidant performance of theadditive of the present invention.

TABLE 7 viscosity increase Additive wt % at 64 h Example 42 Tetramertreated 1.1 143 intermediate Comparative sulfurised 1.1 350 Example 13phenolic

What is claimed is:
 1. A process for preparing an oil-soluble sulfurised phenol additive compatible with nitrile seals which process comprises the steps of: (i) reacting together at a temperature of at least 100° C.: an oil-soluble active sulfur-containing sulfurised phenol intermediate; and an olefin or an acetylenic compound in an amount in excess of the stoichiometric amount required to react with the active-sulfur present in the sulfurized phenol intermediate; and (ii) removing substantially all unreacted olefin or acetylenic compound; provided that, when the olefin is a mono-olefin, it is either unsubstituted aliphatic or is substituted with aromatic functionality, or with one or more hydroxy, amino, cyano, ester, amide carboxylic acid, carboxylate, alkaryl, amidine, sulfinyl, or sulfonyl groups.
 2. A process as claimed in claim 1 wherein the olefin is: (a) an acyclic olefin having at least two double bonds, adjacent double bonds being separated by two saturated carbon atoms; or (b) an olefin comprising an alicyclic ring, which ring contains at least eight carbon atoms and at least two double bonds, each double bond being separated from the closest adjacent double bond(s) by two saturated carbon atoms.
 3. A process as claimed in claim 2 wherein the olefin is a linear terpene.
 4. A process as claimed in claim 3 wherein the terpene is geraniol.
 5. A process as claimed in claim 2 wherein the olefin is 1,5-cyclooctadiene.
 6. A process as claimed in claim 2 wherein the olefin comprises an alicyclic ring containing at least three double bonds, each end of each bond being separated from each adjacent double bond by two saturated carbon atoms.
 7. A process as claimed in claim 6 wherein the olefin is 1,5,9-cyclododecatriene.
 8. A process as claimed in claim 1 wherein the olefin is a mono-olefin.
 9. A process as claimed in claim 8 wherein the mono-olefin is an α-olefin.
 10. A process as claimed in claim 8 wherein the mono-olefin is a C₁₂ propylene tetramer.
 11. A process as claimed in claim 8 wherein the mono-olefin is a compound containing a saturated alicyclic ring and one exocyclic double bond.
 12. A process as claimed in claim 1 wherein the reaction in step (i) is carried out in the presence of a catalyst.
 13. A process a claimed in claim 1 wherein the oil-soluble sulfurised phenol intermediate comprises less than 1000 ppm of chlorine and at least 4% by weight of sulfur and is made by: a) reacting together sulfur monochloride and at least one phenol of general formula II

 wherein R represents a hydrocarbyl radical and y is an integer of 0 to 4, in a reaction mixture and at a temperature in the range of −50 to 250° C. wherein the mole ratio of-phenol: S₂Cl₂ in the reaction mixture is greater than 1.7:1.
 14. A process as claimed in claim 13 wherein the chlorine content is less than 800 ppm.
 15. A process as claimed in claim 1 wherein the oil-soluble active sulfur-containing phenol intermediate is prepared from either sulfur monochloride, sulfur dichloride or mixtures thereof, and has a chlorine content of 100 ppm or greater.
 16. An oil-soluble sulfurised phenol additive compatible with nitrile seals obtained by the process of claim
 1. 17. A lubricating oil composition which comprises lubricating oil as a major component and an oil-soluble sulfurised phenol additive as claimed in claim in
 16. 18. A lubricating oil concentrate which comprises one or more lubricant additives, an oil-soluble sulfurised phenol additive as claimed in claim 16 and lubricating oil.
 19. A process as claimed in claim 1 wherein the amount of olefin or acetylenic compound is at least 100% in excess of the stoichiometric amount required to react with the active sulfur present in the sulfurised phenol intermediate.
 20. A process as claimed in claim 1 wherein the amount of olefin or acetylenic compound is at least 400% in excess of the stoichiometric amount required to react with the active sulfur present in the sulfurised phenol intermediate.
 21. A process as defined in claim 19 wherein substantially all unreacted olefin or acetylenic compound is removed so that unreacted olefin or acetylenic compound in the oil-soluble sulfurised phenol additive is 0.5% by weight or less.
 22. A process as defined in claim 20 wherein substantially all unreacted olefin or acetylenic compound is removed so that unreacted olefin or acetylenic compound in the oil-soluble sulfurised phenol additive is 0.5% by weight or less.
 23. An oil soluble, metal-free sulfurised phenol intermediate or additive of the formula:

wherein R represents a hydrocarbyl radical having 1 to 50 carbon atoms, y is an integer of from 0 to 4 and may be different for each aromatic nucleus, n is an integer of 0 to 20, and x is an integer of from 1 to 4, with the proviso that the average number of carbon atoms per hydrocarbyl radical is sufficient to render said intermediate oil-soluble, said intermediate or additive having a chlorine content of less than 1000 ppm and a sulphur content of at least 4 mass %.
 24. An oil-soluble, metal-free sulfurised phenol intermediate or additive compatible with nitrile seals of claim 23 wherein the chlorine content is less than or equal to 900 and the sulfur content is from 4 to 16 mass %.
 25. An oil-soluble, metal-free sulfurised phenol intermediate or additive compatible with nitrile seals of claim 23 having a level of un-sulfurised phenolic material of up to 20 mass %.
 26. An oil-soluble, metal-free sulfurised phenol intermediate or additive compatible with nitrile seals of claim 24 having a level of un-sulfurised phenolic material of up to 20 mass %.
 27. An oil-soluble, metal-free sulfurised phenol intermediate or additive compatible with nitrile seals of claim 23 having a chlorine content of 500 ppm or less.
 28. An oil-soluble, metal-free sulfurised phenol intermediate or additive compatible with nitrile seals of claim 24 having a chlorine content of 500 ppm or less.
 29. An oil-soluble, metal-free sulfurised phenol intermediate or additive compatible with nitrile seals of claim 26 having a chlorine content of 500 ppm or less.
 30. An oil-soluble, metal-free surfurised phenol intermediate or additive compatible with nitrile seals of claim 23 wherein the sulfur content is from 6 to 12 mass %.
 31. An oil-soluble, metal-free surfurised phenol intermediate or additive compatible with nitrile seals of claim 29 wherein the sulfur content is from 6 to 12 mass %.
 32. An oil-soluble, metal-free sulfurised phenol intermediate or additive compatible with nitrile seals of claim 23 having an active sulfur content of up to 2.43 mass %.
 33. An oil-soluble, metal-free sulfurised phenol intermediate or additive compatible with nitrile seals of claim 31 having an active sulfur content of up to 2.43 mass %.
 34. A phenate or overbased phenate additive having a chlorine content of less than 1000 ppm prepared by reaction of an intermediate or additive of claim 23 with an alkali or alkaline earth metal salt or compound.
 35. A phenate or overbased phenate additive having a chlorine content of less than 1000 ppm prepared by reaction of an intermediate or additive of claim 33 with an alkali or alkaline earth metal salt or compound.
 36. A phenate or overbased phenate additive of claim 34 comprising a neutral or overbased calcium sulfurised phenate.
 37. A phenate or overbased phenate additive of claim 35 comprising a neutral or overbased calcium sulfurised phenate.
 38. A lubricating oil concentrate comprising (a) lubricating oil; and (b) at least one or more oil-soluble sulfurised phenol intermediates or additives of claim 34 present in the concentrate at a level such that a lubricating oil composition prepared from the concentrate comprises 100 ppm or less of chlorine.
 39. A lubricating oil concentrate comprising (a) lubricating oil; and (b) at least one or more oil-soluble sulfurised phenol intermediates or additives of claim 35 present in the concentrate at a level such that a lubricating oil composition prepared from the concentrate comprises 100 ppm or less of chlorine.
 40. A lubricating oil concentrate of claim 39 further comprising one or more ashless dispersants prepared from non-halogenated polymers.
 41. A lubricating oil concentrate of claim 38 further comprising one or more ashless dispersants prepared from non-halogenated polymers.
 42. A lubricating oil composition comprising (a) oil of lubricating viscosity; and (b) one or more oil-soluble sulfurised phenol intermediates or additives of claim 34; the chlorine content of the lubricating oil composition being not more than 100 ppm.
 43. A lubricating oil composition comprising (a) oil of lubricating viscosity; and (b) one or more oil-soluble sulfurised phenol intermediates or additives of claim 35; the chlorine content of the lubricating oil composition being not more than 100 ppm.
 44. A lubricating oil composition of claim 42 additionally comprising one or more ashless dispersants prepared from non-halogenated polymers.
 45. A lubricating oil composition of claim 43 additionally comprising one or more ashless dispersants prepared from non-halogenated polymers.
 46. A method of prolonging the life of elastomeric seals or of reducing ring sticking or both in heavy duty diesel engines which comprises lubricating the engine with an oil-soluble sulfurised phenol additive of claim
 23. 47. A method of prolonging the life of elastomeric seals or of reducing ring sticking or both in heavy duty diesel engines which comprises lubricating the engine with a lubricating oil concentrate of claim
 38. 48. A method of prolonging the life of elastomeric seals or of reducing ring sticking or both in heavy duty diesel engines which comprises lubricating the engine with a lubricating oil composition of claim
 38. 49. A method of lubricating a heavy duty diesel engine comprising lubricating the engine with a lubricating oil composition of claim 42 containing up to 3 mass % of the sulfurised phenol.
 50. The method of claim 49 wherein the composition is exposed to nitrile seals.
 51. An oil-soluble sulfurised phenol additive having a chlorine content of less than 1000 ppm and a delta tensile strength loss of no greater than 46% and/or a delta elongation at break loss of no greater than 46% measured on nitrile elastomers according to test methods DIN 53521 and DIN
 53504. 